Answer: They plan to refinish 82 chairs by method I and 30 chairs by method II.
Step-by-step explanation:
Let x= Number of chairs refinished by method I.
y= Number of chairs refinished by method II.
As per given, [tex]1.5x+2.5y=198\ \ \ (i)[/tex]
[tex]9x+6y=918\ \ \ \ (ii)[/tex]
Multiply 6 on both sides of equation (i) , we get
[tex]9x+15y=1188\ \ \ \ (iii)[/tex]
Subtract (ii) from (iii), we get
[tex]9y=270\Rightarrow\ y=30[/tex]
Put this in (ii), [tex]9x+6(110)=1188[/tex]
[tex]\Rightarrow\ 9x+180=918\\\\\Rightarrow\ 9x=918-180\\\\\Rightarrow\ 9x=738\\\\\Rightarrow\ x=82[/tex]
Hence, they plan to refinish 82 chairs by method I and 30 chairs by method II.